You just received a file from your collaborator: `exons.bed`, which contains a list of exonic regions. As part of your analysis, you would like to merge all overlapping regions into contiguous intervals. This is a perfect job for `bedtools merge`, **but** you keep getting an error when you run the following command: **Your Goal**: Create a file `exons.fixed.bed` from the regions in `exons.bed` so that the following query does not give an error. Use the search and replace command `sed` for making changes to the file.